Magnetic filter



Feb. 18, 1958 Filed Sept. 12, 1955 Fig. l

2 Sheets-Sheet 1 l7 l2 1 I Edward H. Sinclair Grover H. Curtis I4Inventors Attorney Feb. 18, 1958 E. H. SINCI AIR ETAL 2,823,803

MAGNETIC FILTER Filed Sept. 12, 1955 2 Sheets-Sheet 2 7 2| l0 20 A 'I ji f 25 i r \\v 2| 2 24 Fig.5

Fig. 3

Edwclrd H. Sinclair Grover H. Curtis Inventors Attorney United StatesPatent" MAGNETIC FILTER Edward H. Sinclair, Windsor, and Grover H.Curtis, Hartland, Vt., assignors to Sinclair Machine Products, Inc.,Windsor, Vt., a corporation of Vermont Application September 12, 1955,Serial No. 533,726

3 Claims. (Cl. 210-222) This invention relates to filters, and inparticular to oil filters for use on machine tools, although it may beused for other purposes. Oil or other coolant coming from the cuttingtols of automatic screw machines, lathes, drills, milling machines andthe like carries with it a quantity of chips which it is necessary toremove before the oil is recirculated. This is ordinarily done bypassing the oil through a mechanical filter having a screen or areplaceable cartridge which is cleaned or thrown away after it hasbecome clogged. Where the metal being cut is magnetic, as iron or steel,it has been proposed to employ magnets to which the chips will adhere,but the more efiicient such a filter may be the greater will be theadherence between the chips and the magnets, causing great trouble inremoving them from the magnets when it is necessary to clean the filter.

It is one object of the present invention to provide a magnetic filterin which the adherence between the magnets and the chips can beterminated at will by shortcircuiting the magnetic flux. A furtherobject is to provide means for reversing the polarity of the magnets sothat chips of hardened steel which have become permanently magnetizedthrough their contact with the magnets will be repelled rather thanattracted. A further object is to provide an oil filter which can bedisassembled for cleaning without the use of tools. A further object isto provide an oil filter having no disposable element to cause expenseand difiiculty in handling. Additional objects will appear from thefollowing description and claims.

Referring to the drawings,

Fig. 1 is an exploded view of a filter constructed in accordance withour invention, partly broken away in median section;

Fig. 2 is a top view on a reduced scale;

Fig. 3 is a side view on the same scale as Fig. 2;

Fig. 4 is a top plan of the filter with the magnet poles indicated byhatching to show their relationship with the soft iron magnets which dipinto the oil; the magnet poles being shown in the positions which theyoccupy during filtering; and

Fig. 5 is a view similar to Fig. 4 showing the magnet poles rotated sothat they are short-circuited by the soft iron magnets.

The filter, in accordance with the preferred embodiment, has a bodyprovided with a cylindrical cavity 11 in its upper surface, and adownwardly extending flange 12 interiorly threaded at 13. A bowl 14,having a flange 15 at its upper edge, fits within the cavity 16 insidethe threaded flange 12, and bears against a ring packing 17. The flange15 is pressed against the packing 17 by a gland 18 threaded at 19 toengage the threads 13, and having a hand grip 20 by which the bowl canbe removed or replaced without the necessity of using tools. The bowlmay be provided with threads if desired and the gland omitted.

A plurality of soft iron rods 21 are threaded or otherice wise securedto the head 10 with their upper ends flush with the bottom of the cavity11 and their lower portions extending nearly to the bottom of the bowl14. A cylindrical magnet 22, having a central aperture 23 and its wallscut away to form alternating pole pieces 24 and 25, is secured by ascrew 26 and a spacer 27 to the interior of a cap 28 which fitsrotatably over the upper portion of the body 10. When the cap is inposition a pin 29 is driven through it so as to pass through a slot 30in the upper portion of the body 10 and into a hole 31 in the permanentmagnet 22. The pin is preferably filed off flush with the outer surfaceof the cap to prevent its unauthorized removal for the purpose of takingaway the relatively expensive magnet.

The slot 30 permits a limited rotation of the cap 28 and the permanentmagnet 22 relative to the rods 21, preferably enough to carry eachpermanent magnet pole from one soft iron rod to the next. The permanentmagnet poles 24 and 25 are alternately north and south, so that thisamount of rotation will reverse the polarity of the soft iron temporarymagnet rods. If a hard steel chip has adhered to one of the rods it willitself become permanently magnetized, and by reversing the polarity ofthe temporary magnet rod it will be repelled rather than attracted andleft free to drop off. Ifthe permanent magnet poles are rotated to theintermediate position of Fig. 5 they will be short-circuited through thesoft iron tops of the rods and the latter will be left unmagnetized.Temporarily magnetic chips such as those of soft steel, will thus falloil? into the bowl 14 and can be removed. Any chips still adhering tothe rods can be readily wiped off with the magnet 22 in the off positionof Fig. 5.

The body 10 is provided with passages 32, one at each side, connectingby short bores 33 with the cavity 16, so that as shown in Figs. 2 and 3the filter can be connected in the oil line 34.

What we claim is:

l. A magnetic filter comprising a vessel through which the liquid to bepurified passes, a plurality of soft iron rods extending into theinterior of the vessel in a circular series, and a cylindrical permanentmagnet having spaced poles equal in number to the number of rods andextending parallel to the axis of the cylinder into contact with one endof the series of rods, and means for mounting the permanent magnet forrotation from a position in which each pole contacts the end of one rodto a position in which each pole makes contact with two adjacent rods.

2. A magnetic filter having a body portion provided with entrance andexit ports for the liquid to be purified, a vessel detachably secured tothe body portion and bridging the ports so that the liquid may flowthrough said vessel, a circular series or" soft iron rods passingthrough the body portion and extending at one end into the vessel, acylindrical permanent magnet having spaced poles equal in number to thenumber of rods and extending parallel to the axis of the cylinder intocontact with that end of the series of rods remote from the vessel, andmeans for mounting the magnet for rotation about the axis of thecircular series of rods an amount equal to one-half the angular distancebetween adjacent rods, whereby the magnet may be located with each polein contact with one of the rods or in a position in which each polebridges across a pair of adjacent rods.

3. A magnetic filter having a body portion provided with entrance andexit ports for the liquid to be purified, a vessel detachably secured tothe body portion and bridging the ports so that the liquid may flowthrough said vessel, a circular series of soft iron rods passing throughthe body portion and extending at one end into the vessel, a cylindricalpermanent magnet having spaced poles equal in number to the number ofrods and extending parallel to the axis of the cylinder into contactwith that end of the series of rods remote from the vessel, and meansfor mounting the magnet for rotation about the axis of the circularseries of rods an amount equal to the angular distance between adjacentrods, whereby the magnet may 5 be located with each pole in contact witheither of two adjacent rods or in an intermediate position in which eachpole bridges across a pair of adjacent rods.

References Cited in the file of this patent FOREIGN PATENTS an... I. i

